This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The overall hypothesis of this study is that elevated sex steroid levels may account for some of the hormone-related conditions that follow throughout life in African-American females, including leiomyomas, endocrine related cancers, and protection from osteoporosis. If so, it may begin to be understood the contribution to these processes, both protective and additive, in Black females, and also will allow differences in sex steroid levels in the normal menstrual cycle, as well as to identify mechanisms. The study will further propose to examine the effects of sex steroids on an end organ-in this case bone mineral density and architecture. The purpose of this study is to see if levels of female compared to white females. If so, we may begin to understand their contribution to certain illnesses in Black females allowing us to improve methods of preventing medical these illnesses. The study will measure differences in hormone levels in the normal menstrual cycle, as well as determine reasons for these differences.